Spun yarn and its doubled yarn



MASAAKI TABATA ETAL 3,501,907

SPUN YARN AND ITS DOUBLED YARN March 24, 1970 6 Sheets-Sheet 1 Filed Dec. 15, 1967 March 24, 1970 MASAAKI TABATA ETAL 3,501,907

SPUN YARN AND ITS DOUBLED YARN Filed Dec. 15, 1967 6 Sheets-Sheet 2 March 24, 1970 MASAAKI TABATA ETAL 3,501,907

SPUN YARN AND ITS DOUBLED YARN 6 Sheets-Sheet 5 Filed Dec. 15, 1967 VAURVATURE B Fig. 6

o o 7 o b IOO- UNTWISTING RATE in March 24, 1970 MASAAKI TABATA ETAI- 3,501,907

SPUN YARN AND ITS DOUBLED YARN 4 6 Sheets-Sheet 4 Filed Dec. 15. 1967 March 1970 MASAAKI TABAfA ETAL 3,501,907

SPUN YARN AND ITS DOUBLED YARN Filed Dec. 15. 1967 6 Sheets-Sheet 5 Fig. 8A Fig. 86

Fig 85 March 24, 1970 MASAAKI TABATA, ETAL 3,501,907

SPUN YARN AND ITS DOUBLED YARN Filed DEC. 15, 1967 6 Sheets-Sheet 6 United States Patent US. Cl. 57-140 6 Claims ABSTRACT OF THE DISCLOSURE An improved spun yarn of the invention is provided with twist configuration characterized by fibers maintained in the respective forms of spiral having uniform pitch and diameter of coils of the respective spirals. The form of spiral of fibers in an inner layer with respect to an axis of the yarn is provided with a smaller number of coils of spiral and smaller diameter of the spiral while the form of spiral of fibers in an outer layer with respect to the yarn axis provided with larger number of coils of spiral and larger dameter of the coils of the spiral, further the respective spiral of fibers in the inner and outer layer is provided with almost uniform diameter with respect to the axis of yarn. An improved blended yarn provided with the above-mentioned twist configuration is also disclosed. Further a process for manufacturing the abovementioned blended yarn is also disclosed.

The present invention relates to an improved spun yarn having novel configuration of twist and superior mechanical properties such as excellent resiliency and soft feeling of touch, and also the method for manufacturing the same.

Generally, it is well-known that twisting in the spinning operation is an inevitable operation for forming yarn made from a fleece comprising a plurality of fibers which are continuously gathered and aligned along their lengthwise direction to bestow the strength of the yarn. The twisting of yarn by the ring spinning frame, flyer spinning frame, are also well-known arts. These conventional twisting methods twist the yarn in the same way, that is, one end of the bundle of fibers is fixed while the other end of the bundle of fibers is turned continuously by the rotation of the package of twisted yarn.

Generally, if the fibers of the fiber strand before twisting can be maintained in the twisting operation and the relative positions of each fiber in the fiber strand do not change even after the twisting operation, the fibers are occupied in the respective layer of the configuration of yarn. Consequently, the projection length of the fiber toward the axis of the yarn varies in accordance with the layer wherein the fiber is occupied, in other words, the projection length of the fiber disposed in the outer layer of the yarn is shorter than that of the fiber disposed in the inner layer of the yarn. In fact, it cannot be considered that the fibers are stretched to form the abovementioned configuration of yarn while the twisting operation is being performed. Consequently, the fibers of yarn across each other and there is no simple cylindrical layers of fiber in the twisted yarn, in other words, each fiber comes into the inner portion of yarn and goes out to the outer portion of yarn, or vice versa. The above-mentioned phenomenon is generally called migration in the field of textile technology. A yarn having the configuration of migration has such defects as the stiffness of the yarn increases with continuance of twisting while the resilience of the yarn degrades with decrease of the twisting. Consequently it is almost difficult to produce spun yarn having 3,501,907 Patented Mar. 24, 1970 ice soft feeling of touch and sulficient resiliency by the conventional twisting methods.

The principal object of the present invention is to provide improved spun yarn having soft feeling of touch and sufiicient resiliency and the process for manufacturing the same.

Another object of the invention is to provide a possibility for producing fabric having superior handling quality suitable as a material for making clothes by the improved spun yarn according to the present invention.

A further object of the invention is to provide an improved blended yarn having uniform blending of fibers and superior bulkiness, and a process for manufacturing the same.

A still further object of the invention is to provide a doubled yarn comprising a plurality of single yarns having a novel configuration of fibers and a process for manufacturing it.

Further features and advantages of the invention will be apparent from the ensuing description with reference to the accompanying drawings to which the scope of the invention is in no Way limited.

FIG. 1 is a skeleton sketch of an embodiment of the spinning device for manufacturing the yarn of the invention,

FIG. 2 is an explanatory drawing of the twisting mechanism of the spinning device shown in FIG. 1,

FIG. 3 is an enlarged side view of an embodiment of the spun yarn produced by the spinning device shown in FIG. 1,

FIGS. 4A, 4B and 4C are explanatory drawings showing the shapes of the fibers in the conventional yarn and the yarns of the present invention, respectively,

FIG. 5 is an explanatory diagram showing the bending moment of yarn,

FIG. 6 is a diagram showing the relation between the residual strength of yarn and the rate of back twist for the conventional spun yarn and the yarn of the present invention,

FIG. 7 is a skeleton sketch of another embodiment of the spinning device for manufacturing the yarn of the invention,

FIGS. 8A, 8B and 8C are several embodiments of the spinning device for producing blended yarn having the configuration of fibers shown in FIGS. 3B and 3C,

FIG. 9 is an enlarged cross sectional view of the blended yarn produced by the spinning device shown in FIG.

FIG. 10 is an explanatory drawing for showing an embodiment of the apparatus for manufacturing the doubled yarn having the novel configuration of yarns without migration.

To obtain soft feeling of touch and superior resiliency of yarn, the yarn must have a novel configuration without migration. Such yarn can be manufactured by the spinning device shown in FIG. 1. The twisting mechanism of the spinning device shown in 'FIG. 1 differs completely from that of the conventional twisting mechanism, that is, one end of the bundle of fibers is turned while the other end of the bundle of fibers does not receive restriction during the twisting operation. A detailed illustration of the above-mentioned twisting mechanism and its operation are as follows:

The bundle of fibers 1 is supplied successively from a draft device comprising a trumpet 2, a pair of back rollers 3, 3', a pair of middle rollers 4, 4', and a pair of front rollers 5, 5', and the supplied bundle of fibers is sucked into a guide inlet 7 of a supply device 8 wherein sucking force is caused by compressed air supplied from a supply front rollers 5, 5', and fed to a rotor through the delivery pipe 9 of the supply device 8 by the air stream feeding means. The outlet portion of the delivery pipe 9 points toward the inside wall of the rotor 10 as shown in FIGS. 1 and 2. The rotor 10 is formed in a pot-like shape and is supported by a vertical cylindrical axis 13 supported by a machine frame 11 through a bearing 12 and is rotated at a high rotating speed by means of the driving belt 16. The liberated or loosened fibers are ejected against the inside wall of the rotor 10, deposited successively upon it by the centrifugal force and air stream, consequently, the deposited fibers on the inside wall of the rotor 10 are rotated at a high rotating speed together with the rotor 10 on whose wall they adhere. The liberated fibers thus deposited upon the inside wall of the rotor 10 are collected to form a bundle of yarn and twisted in a form of a complete spinning yarn 15 and taken up into a drum (not shown) by a pair of take-up rollers 19.

In the above-mentioned twisting mechanism, theliberated fibers 1' adhere to the inside wall of the rotor 10 by means of the centrifugal force and are accumulated successively, whereby self-doubling effect is caused to the bundle of fibers taken up from the inside Wall of the rotor 10. The word self-doubling effect is explained as follows. Generally, in the spinning operation, the uneven thickness of the products such as sliver or roving is decreased by so-called doubling of a plurality of the products during the drafting operation. This effect is called doubling effect, however in the present case, only the liberated fibers successively fed from the delivery pipe 9 are doub ed by means of the accumulation upon the inside wall of the rotor 10 in a similar manner as cutting a pack of cards, in the other words, the supplied bundle of fibers 6 is liberated into numerous individual fibers and doubled successively by the above-mentioned manner, consequently, the uneven thickness of the supplied bundle of fibers 6 can be reduced remarkably. The abovementioned effect is hereinafter called self-doubling effect. The fiber bundle taken from the inside wall of the rotor 10 is positively turned at the position the bundle of fibers is removed from the inside wall of the rotor while each fiber of the fiber bundle does not receive restriction to change them in the relative aligned position of fibers because the fiber bundle is accumulated upon the inside wall of the rotor 10 by the centrifugal force.

As mentioned above, the liberated fibers supplied from the pipe 9 to the inside wall of the rotor 10 are accumulated in a uniform condition of alignment upon the inside wall of the rotor 10 while being provided with the selfioubling effect. Now supposing that the inside radius of the rotor is R in meter, number of revolutions of the rotor is M r.p.m., the surface speed of the inside wall of :he rotor 10 is V meter per min., taking-off speed of the nundle of fibers from the inside wall of the rotor 10 is W neter per min., an arbitrary point on the inside wall of :he rotor is designated as point P, and the bundle of fibers s taken-off from the inside wall of the rotor 10 at the Josition designated by point P at the time function t=T, :he taking-off point on the inside wall of the rotor 10 :rave's along the inside wall of the rotor 10 at a speed )f W meter per min. while taking off the bundle of fibers :ontinuously from the inside wall of the rotor 10, and be taking off point returns to the original point P at the .ime t=T+21rR/W min., that is, after a passage of 21rR/W him. While the taking off point of the bundle of fibers .ravels as mentioned above, the rotor 10 rotates 21rR/W: V/W turns. As the liberated fibers are coninuously blown to the inside wall of the rotor 10 while ravelling the taking off point travels along the inside Wall )f the rotor, it can be considered that the liberated fibers tre blown V/W times upon the position designated by the aking-otf point P until the taking-off point returns to the )riginal point P. Now supposing the average number of ibers contained in the cross-section of the supplied roving s N, the draft ratio of the draft element is D, the surface peed of he front roller is U meter per min, the supplied roving is drafted at V/U times while passing through the draft zone between the nip point of the rollers 5, 5" and the inside wall of the rotor 10, consequently, the bundle of fibers, considered as the average number of fibers in the cross section is n NU/DV, adheres upon the inside wall of the rotor at each revolution of the roof 10. Consequently, the bundle of fibers, wherein the average number of fibers in its cross-section is n, are doubled by V/ W. In other words, the drafted roving in the libera ed condition is self-doubled by V/ W. The above-mentioned doubling operation is performed at any position in the inside wall of the rotor. The fibers accumulated on the inside wall of the rotor only maintain their relative positions as a unit of the bundle of fibers chiefly by the centrifugal force, further the taking off points of the bundie of fibers from the inside wall of the rotor 10 are not fixed at one taking off point P. Consequently, no migration takes place during the twisting operation according to the above-mentioned embodiment of the invention, and a spun yarn having uniform thickness due to the selfdoubling effect of the rotor 10 can be manufactured.

When taking off the bundle of fibers continuously from the inside wall of the rotor 10, it is necessary to keep th force restricting the free turning of the bundle of fibers at the taking-off point on the inside wall of the rotor 10 at a suitable magnitude. The force restricting the free turning of the bundle of fibers is mainly the frictional force between the bundle of fibers and the inside wall of the rotor 10. The abovementioned frictional force may be defined by the product of centrifugal force working on the bundle of fibers by coefficient. of friction between the bundle of fibers and the inside wall of the rotor 10. According to our experimental test, when the diameter of the largest portion of the rotor 10 is 50 mm., the rotating speed of the rotor 10 is 30,000 r.p.m., the preferable coefficient of friction between the bundle of fibers and the inside wall of the rotor 10 is in a range from 0.2 to 0.7. The abovementioned coefficient of friction was measured by the wellknown Roder method at a linear speed of 50 meters per minute. The metallic inside wall of the rotor provided having a roughened plated surface is suitable for obtaining the above-mentioned preferable condition.

To confirm the configuration of the spun yarn shown in FIG. 3, microscopic tests were performed, and it was noticed that no migration had taken place in the spun yarn of the invention. As is clearly shown in FIG. 3, in spite of the configuration of yarn wherein the number of spiral coils of the fiber positioned at an inner layer of the yarn is less than that of the fiber positioned at an outer layer of the yarn, each fiber is formed with a plurality of spirals or helices aligned along its lengthwise direction and each spiral is provided with almost uniform shape. In the specification, the inner layer of the yarn is defined as that position of the fiber which is closer to the axis of the yarn with respect to the cross-section of the yarn, and vice versa. Consequently, there is no definite boundary between the outer layer and the inner layer of the yarn, in other words, when comparing the position of two fibers in the yarn, the fiber positioned closer to the longitudinal axis of the yarn is considered as the fiber positioned at the inner layer of the yarn while the fiber positioned at a longer distance from the longitudinal axis of the yarn is considered as the fiber positioned at the outer layer of the yarn. Next, the term of the difference in number of spiral coils means that the fibers of the yarn have different spiral turns or different fiber pitch. All cases of changing spiral of fibers may be considered, in other words, the continuous changing of fiber spiral or discontinuous changing of fiber spiral from the outer layer to the inner layer may be considered.

As mentioned above, it is one of the features of the yarn according to the present invention that the number of spiral coils of the fibers in the outer layer of yarn is larger than that of fibers in the inner layer of yarn. The difference in the configuraticm 9f ya n between the conventional yarn and the yarn of the present invention is explained in detail as follows.

The shape of two fibers contained in the conventional yarn and the yarns of the present invention are shown in FIGS. 4A, 4B and 4C, wherein projections of two fibers to a plane parallel to the yarn axis are shown, respectively. In these drawings, a, c and e represent each fiber in the outer layer of the respective yarns while b, d and 1 represent each fiber in the inner layer of the respective yarns.

Supposing the number of fibers contained in the abovementioned yarns are the same and the stress caused by the bending deformation of the above-mentioned yarns in the same loading condition are considered. As is wellknown, the bending deformation of the outer layer is larger than that of the inner layer with regard to the yarn axis, consequently, the fiber of the outer layer contributes to the stress of the yarn more than the inner layer of the yarn.

On the other hand, as it is well-known from a model of a coil spring, the pitch of the coil is smaller, in other words the larger the number of coils, the smaller the resilience to the bending deformation is. As mentioned above, the yarn of the present invention has a particular twist configuration wherein the number of coils of spiral of the fiber in the outer layer of the yarn is larger while that of the fiber in the inner layer of the yarn is smaller, in other words, the fiber in the outer layer of the yarn has a weaker resistance to the bending deformation while the fiber in the inner layer of yarn has a stronger resistance. Consequently, it is clearly understood that the yarn having a twist configuration composed of fibers such as a and [2 shown in FIG. 4A has a stronger resistance to the bending deformation than the yarn having a twist configuration composed of fibers such as c and d, e and f shown in FIGS. 48 and 4C, respectively. Concerning the torsional deformation, the yarn of the invention is easier to twist than the conventional yarn by the same reason as mentioned above. Therefore, the yarn of the invention shown in FIGS. 4B and 4C is softer than the conventional yarn shown in FIG. 4A.

In the yarn of the present invention, the interference of the fibers in the inner layer or group to the fibers in the outer layer or group is very small, in other words, the fibers in the inner layer and the outer layer of the yarn can be deformed independently from each other. In addition, the inner and outer layers of fibers have their respective helical convolutions irregularly and randomly positioned with respect to each other, or, in other words, the convolutions are out of phase with each other as seen in FIGS. 3, 4B and 4C. Consequently, the frictional resistance between the fibers in the inner layer and the outer layer can be considered as being very small.

On the other hand, it is well-known that the friction between the individual fibers dominates the resiliency of the yarn in a small range of the deformation. Consequently, it can be considered that the yarn of the invention has superior resiliency.

The above-mentioned features of the yarn of the present invention are more clearly understood by the following examples.

EXAMPLE 1 A small amount of fibers dyed in black color was blended when spinning a yarn of polyester staple fiber and the yarn manufactured by the method shown in FIG. 1. p

The rotation speed of the rotor was 31,000 rpm, and the above-mentioned coetficient of friction measured by the Roder method was 0.46.

The yarn produced was mounted with a tricresylphosphate liquid, then the yarn was observed with a microscope by means of inserting sensitive filter (530 mp.) to a polarized light microscope with crossed-nicol. It was found from this test that there was no migration.

6 EXAMPLE 2 A spun yarn of polypropylene was manufactured in the same spinning condition. The mechanical properties of the yarn are shown in Table 1, together with the me chanical properties of the conventional yarn manufactured by the ring spinning system for comparison purpose.

TABLE 1 Yarn of the invention Conventional Kind of yarn yarn Yarn count in English system Number of twist, turn/inch Breaking strength in g Breaking elongation in percent Bending stiffness:

Yarn:

CD F...

F/CD Knitted cloth:

CT F

176B Bulkiness in cm. I Coefficient of compressibility the points A and B is represented by It is considered that the test piece is easier to bend, if the value of CD is larger.

Further, the distance between points A and B is represented by F which is considered as a frictional force at the time of bending deformation of the test piece in a sheet form. Then the value of F 6 5 is calculated, and it is considered that the resilience of the test piece in a sheet form is larger if the value of F C" D is smaller.

The above-mentioned method of estimation was confirmed by results obtained by many experimental tests, further the results obtained by the present method exhibited the so-called functional feeling or handling quality of the test piece of cloth. Thirty pieces of yarn aligned in a parallel condition with 20 mm. width were prepared for the testing yarn. The test pieces of the knitted cloth were cut in a width of 20 mm. The distance between the grips was 4 mm. As indicated by the mechanical properties of the yarn shown in the Table 1, it is clear that the yarn of the present invention has superior resiliency and soft feeling of touch.

In Table 1, the bulkiness of the test piece was measured with the conventional instrument for measuring thickness of the test piece continuously under a changing load. The original thickness of the test piece was measured under a load condition of 2 g./cm. and the specific volume of the test piece was calculated. As shown in Table 1, the yarn of the invention is more bulky than the conventional yarn.

As already explained, the yarn of the present invention has a novel configuration of yarn wherein there is no migration and each fiber contained in the yarn is provided with a plurality of coils of spiral with almost uniform diameter with respect to the yarn axis. Consequently, when the yarn of the present invention is untwisted the yarn can maintain its configuration of yarn but in case of the conventional yarn, the yarn loses its twisted configuration by untwisting and then loses the strength of yarn. To make clear the difference of the effect of untwisting of the yarns of the present invention and the conventional yarn, the relation between the residual strength of yarn and the rate of back twist of both yarns are shown in FIG. 6 wherein curve b represents the case of the convenzional yarn while curve a represents the case of the present .nvention.

As is clearly shown in the diagram, the residual strength )f the yarn at the rate of back twist of 100% is still more :han nill and the residual strength of the yarn at the rate )f back twist of 75% is more than 30% of the original rtrength. As indicated by the experimental test, it is imiossible to impart to the spun yarn of the invention a 10 twist configuration, consequently, it is clearly under- ;tood that the spiral configuration of fibers in the outer ayer and the inner layer of the yarn is not uniform. in the above-mentioned illustration, the residual strength )f the yarn, and the rate of the back twist are defined as follows:

g nal breaking strength of yarn X 100% Rate of back twisting Number of turns for back twisting Original number of twist The above-mentioned yarn of the present invention can 3e manufactured by another method as shown in FIG. 7. [n the drawing of FIG. 7, a draft element comprises 1 pair of back rollers 22, 22, a pair of apron rollers 23, 23', a pair of draft rollers 24, 24', and further a pair of front rollers 25, 25'. After the above draft elenent, a twisting and winding device of the ring-traveller :ystem is installed. A roving 21 is supplied to the draft :lement through the back rollers 22 and 22, and then he supplied roving is drafted and is provided with twist luring the winding operation, During the above-mentioned :pinning, twisting and winding operations, a spun yarn Z8 is supplied to the draft rollers 24, 24', and guide 'oller 26. In this case, the roller gauge g between the lip point of the front rollers 25 and 25' and the draft "ollers 24 and 24 is fixed slightly longer than the maxinum length of the fiber contained in the roving 21. urther, the number of twists of the supplied yarn 28 s the same as that of the spun yarn produced by the present method while the direction of the twist of the ;upplied yarn is opposite that of the spun yarn produced )y the present method. In the above-mentioned spinning )peration, the fibers in the supplied spun yarn 28 are atretched at the stretch zone between the rollers 25, 25' 1nd the rollers 24, 24, next the elongation of the stretched zarn is recovered elastically the instant the yarn 28 is lelivered from the front rollers 25, 25 and untwisted. the stretch ratio between the stretch zone is preferably from 1.10 to 1.15 in accordance with the elongation [almost 2%) of the supplied yarn 28 caused by the mtwisting. On the other hand, after the drafting of the ;upplied roving, the drafted bundle of fibers delivered from the front rollers 25 and 25 is provided with twist. Consequently, the product of the present device comprises a bundle of fibers without spiral at the core por- :ion of the product and spiraled fibers from the roving :overing the core portion of the product.

Recently, the blending of several kinds of fibers has Jeen developed for manufacturing blended spun yarn. )ne remarkable example is a blended yarn of acrylic iber with another kind of fiber which has superior bulki- 1ess. The high-bulky acrylic blended yarn has a large narket in the field of knitted wear. The properties such is bulkiness of the blended yarn mentioned above can )6 improved remarkably by applying the particular coniguration of yarn of the present invention.

Generally one of the features required in the blended {3H1 is uniform condition of the blending fibers. In case )f knitting yarn such as high-bulky acrylic yarn, some lesirable mechanical properties such as soft feeling of :ouch and sufficient resiliency of the blended yarn, etc., are always required. As the spun yarn of the invention has a particular configuration without migration, the above-mentioned preferable mechanical properties can be acquired by the configuration of the yarn of the invention. Further, very superior blending effect, which was not obtained by the conventional spinning method can be obtained by the self-doubling effect of the rotating rotor of the spinning device shown in FIG. 1.

Some embodiments of the manufactured blended spun yarn according to the present invention are shown in FIGS. 8A, 8B and 8C. These manufacturing methods are characterized by the process comprising liberating a plurality kinds of bundled fibers in a fluid stream, carrying the liberated fibers to the inside wall of a rotor through a delivery pipe or the respective delivery pipes, accumulating the supplied liberated fibers of a plurality kinds of fibers upon the inside wall of the rotor continuously by its centrifugal force and the air stream, removing the accumulated bundle of blended fibers from the inside wall of the rotor while twisting, removing the twisted bundle of blended fibers through an aperture disposed to the central bottom portion of the rotor and winding to a suitable drum. In the above-mentioned explanation, the term plurality kinds of fibers means different kinds of fibers in staple form or fibers having different fineness or cut length, or different mechanical properties or different colors.

Referring to FIG. 8A, single roving 31, a blend of two different fibers, is supplied to the draft element, while in FIG. 8B two rovings 31 and 31' comprising the respective fibers which differ from each other are supplied to the draft element in the doubled condition and the liberated different fibers in the double rovings are carried to the inside surface of the rotating rotor 40 through a single delivery pipe 39. On the other hand, in FIG. 8C, two rovings 31 and 31' comprising the respective fibers which differ from each other are supplied to the respective draft element separately, and the respective liberated fibers are supplied to the inside surface of the same rotor 40 through the respective delivery pipes 39 and 39' separately. By the above-mentioned function of the rotor 40, the self-doubling effect can be obtained in the three cases mentioned above, consequently, a very uniform blending effect can be obtained. That is, as already illustrated in the explanation of the function of the rotor shown in FIG. 2, supporting the average number of fibers contained in the respective two kinds of roving are N and N, the bundle of fibers comprising a plurality of fibers, which number n or n' in its cross section is calculated as n=NU/DV or n=NU/DV, are doubled and adhered upon the inside wall of the roller 40. The number of the above-mentioned doubling can be calculated as V/ W. Consequently, the bundle of fibers taken from the inside wall of the rotor 40 contains two kinds of fibers comprising a plurality of fibers represented by the following equation (N +N')/D U/ W, the perfect blending condition similar to the doubling of V/ W bundles of fibers can be expected. Further, by the twisting of the above-mentioned system, the blended yarn has novel configuration without migration, consequently the blended yarn having superior mechanical properties such as 2 soft hand feeling, high bulkiness, strong resiliency, etc., can be obtained. The mechanism of the spinning device shown in FIGS. 8A, 8B and 8C are almost the same as that shown in FIG. 1, in which the spinning material is supplied to the back rollers 35, 35' and drafted by the draft zone comprising the back rollers 35 and 35', middle rollers 36 and 36 apron 36" and front rollers 37 and 37', then the drafted bundle of fibers is sucked into the delivery pipe 39 or 39, and carried to the rotating rotor 40 in the liberated condition by the air stream, and the accumulated bundle of fibers is taken off from the inside wall of the rotor 40 and carried to the outside of the rotating rotor through a bottom aperture disposed to the central hollow shaft 40' of the rotor 40 during the twisting operation, and the manufactured blended yarn 44 is wound on a drum (not shown) by a conventional winding means.

EXAMPLE 3 A double roving comprising a roving dyed in black color and a roving without dyeing was supplied to the spinning device as shown in FIG. 8B and a blended yarn of so-called pepper and salt color was produced. The spinning condition of the yarn was as shown in the following table.

Referring to FIG. 9, it was noticed that the fibers contained in the yarn were blended satisfactorily as shown in the enlarged sketch of the cross-section of the yarn of the example.

It is one of features of the invention that the blended yarn having satisfactory blending of fibers can be easily manufactured by the method of the invention in spite of the very short-cut spinning system whose blending effect is superior to the blending effect in the conventional spinning system wherein the doubling number corresponds to V/ W.

In the above illustration, some embodiments for blend-- ing two kinds of fibers are explained and the principle of the blending of the present invention is not restricted to the blending of more than two kinds of fibers.

Further, the principle of the blending of the present invention may be applied to the so-called direct spinning system, that is, two kinds of tows are supplied to the draft-cut device of the respective direct spinning equipment separately, next the bundles of fibers produced by the draft-cut device are supplied to a pair of front rollers corresponding to the front rollers shown in FIG. 8A or 8B or 80, separately or in a doubled condition, then fed to the twisting device in the same way as shown in FIGS. 8A or 8B or 80.

The conventional doubled yarn, such as two ply or three ply yarn, comprises a plurality of single yarns having a configuration or migration. Further, these doubled yarns are always twisted. Consequently, the feeling by hand is rather hard in comparison with the single yarn. However, a doubled yarn having a soft hand feeling, superior resiliency and high bulkiness can be produced by using the yarn of the present invention. Further, the processes for manufacturing the double yarn can be reduced, in other words, the rewinding process and the twisting process of the conventional method can be omitted, consequently, some defects of the double yarn such as pilling or roughening of the surface yarn caused by the rewinding or twisting operation can be eliminated by the method of the present invention.

Referring to FIG. 10, an embodiment of the equipment for producing double yarn of the invention comprises a pair of spinning devices and a device for doubling and twisting the products of the two spinning devices continuously. Each spinning device comprises a trumpet 50, a pair of back rollers 51, 51', a pair of middle rollers 52 and 52', a pair of front rollers 53 and 53', and further a twisting device comprising a rotor 56 and a supply member 55 for supplying the product 54 delivered from the front rollers 53 and 53 to the rotor 56. The spinning operation of each spinning device is performed in the same manner as explained in the first embodiment shown in FIGS. 1 and 2. The twisted products 58 and 58' are taken from the aperture of the respective rotors 56, 56 by the respective take up rollers 57, 57', then combined by a yarn guide 59, and next twisted by a conventional ring twister while the product 62 is winding around a bobbin 61. The ring twister comprises a spindle 65, ring 63, traveller 64, balloon control rings 67 and 67, and a snail wire 60. In the above-mentioned method, double yarn comprising more than three single yarns can be produced by the same principle, and further many kinds of doubled yarns having a particular configuration can be produced by combinations of the rotors rotating in different directions or rotating at different speeds.

While the invention has been described in conjunction with certain embodiments thereof it is to be understood that various modification and changes may be made without departing from the spirit and scope of the invention.

What is claimed is:

1. A spun yarn having an improved twist configuration comprising: an outer and an inner group of concentrically and helically twisted fibers, the outer group of fibers having a larger fiber pitch and a larger fiber helical diameter than the fibers constituting the inner group, said outer and inner groups of fibers having their respective helical convolutions irregularly and randomly positioned with respect to each other, and the fibers constituting both said inner and outer groups having, respectively, uniform helical diameters along the longitudinal yarn axis.

2. A spun yarn according to claim 1, wherein said yarn has a residual breaking strength greater than zero after 100% back-twisting and a residual breaking strength of at least 30% after back-twisting where the degree of back-twisting is represented by,

Number of turns for back-twisting Original number of twist and the residual breaking strength is represented by,

Breaking strength of back-twist yarn Original breaking strength of yarn References Cited UNITED STATES PATENTS 2,817,947 12/1957 Strang 57-12 2,911,783 11/ 1959 Gotzfried 5758.95 3,177,642 4/1965 Korikovsky 57-34 FOREIGN PATENTS 181,800 4/1955 Austria.

STANLEY N. GILREATH, Primary Examiner W. H. SCI-IROEDER, Assistant Examiner US. Cl. X.R. 5758.89, 139

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 501, 907 Dated March 24, 1970 Inventor(s) Masaaki TABATA et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 23, "dameter" should read -diameter--;

and

Column 10, line 25, "larger" should read --smaller-.

QIGNEB AND REALED (S Attest:

Edward M. Fletcher, It.

WILLIAM E. warm JR- Attestmg Offieer Commissioner of Patants FORM PO-IOSO |10-69) USCOMM-DC 80875-P6B i u s. covnmazm nmmus orncz; nu o-su-su 

